Conventional production of inorganic filler-containing polyolefin resin compositions has been accomplished by the following procedure.
(1) The polyolefin resin obtained by polymerization is stocked as a powder, or small amounts of additives such as antioxidants are combined therewith before kneading and pelletization to make pellets, which are packed into paper bags and stocked in a storage facility.
(2) For production of the inorganic filler-containing polyolefin resin composition, the stocked polyolefin resin powder or pellets are transported to a compounding facility or compounding factory.
(3) The powdered or pelletized polyolefin resin, the inorganic filler and the various additives are separately supplied to a pellitizer for kneading and pelletizing, or else are simultaneously mixed in a high-speed mixer or the like and then kneaded and pelletized with a pellitizer.
This procedure, however, requires a storage facility such as a warehouse and a special pelletizing apparatus, which leads to increased production costs including transport of the intermediate materials. In addition, it is often difficult to obtain stable product quality.
It is an object of the present invention to solve the aforementioned problems relating to production of inorganic filler-containing polyolefin resin compositions, and specifically to provide a highly economical process and apparatus which allow production of an inorganic filler-containing polyolefin resin composition with excellent physical properties.